This invention relates to hematology systems and methods. More specifically, this invention relates to systems and methods for analyzing blood samples to identify, classify, and/or quantify basophils in a sample of blood.
Basophils are a white blood cell (WBC) sub-population, which represent 1% or less of the total WBC count for a normal blood sample. Basophils are the least common sub-population of WBCs. Clinically, basophils are primarily involved in certain inflammatory and allergic reactions. Basophils discharge immune system mediators, such as histamine, serotonin, and heparin, to assist the flow of blood and to prevent blood clotting.
Traditionally, basophils are identified and counted manually by examination of microscope slides containing blood sample smears. The precision and accuracy of reviewing slides manually, however, is questionable because basophils are in such low concentrations relative to other WBC sub-populations. Furthermore, the need for well-trained medical technologists, and their associated cost of labor, makes manual review of slides even less commercially viable.
Alternative techniques for basophil detection include the use of antibodies in a flow cytometry analysis system. Numerous antibodies, such as, for example, CD203c, CD63 and FCεR1, were found to be sensitive and specific to basophil surface antigens. However, the cost of basophil antibody assays, the lengthy sample preparation and measurement process, and the requirement of a certified medical technologist having flow cytometry experience, make flow cytometry assay methods unpopular for most hospitals and laboratories.
Instead, basophils are most commonly reported as “best guess” estimates on automated, five-part differential hematology analyzers. In practice, the development of an accurate and efficient basophil assay has been a challenge because: (1) each blood sample is analyzed in less than a minute, including sample aspiration, sample-reagent interaction and incubation, as well as sample measurement, which is an insufficient time period for basophil identification; (2) basophil events number less than 1% in most blood samples; (3) basophils and lymphocytes share similar optical scattering characteristics, thus increasing the likelihood of misidentification; and (4) assays specifically designed for basophils would greatly increase the complexity and cost of the system.